209149931 has 2 divisors, whose sum is σ = 209149932. Its totient is φ = 209149930.

The previous prime is 209149909. The next prime is 209149939. The reversal of 209149931 is 139941902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209149931 - 2²² = 204955627 is a prime.

It is a super-2 number, since 2×209149931² = 87487387274609522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (209149939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104574965 + 104574966.

It is an arithmetic number, because the mean of its divisors is an integer number (104574966).

Almost surely, 2^209149931 is an apocalyptic number.

209149931 is a deficient number, since it is larger than the sum of its proper divisors (1).

209149931 is an equidigital number, since it uses as much as digits as its factorization.

209149931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 209149931 is about 14462.0168372188. The cubic root of 209149931 is about 593.5890878300.

The spelling of 209149931 in words is "two hundred nine million, one hundred forty-nine thousand, nine hundred thirty-one".